EARLY Pregnancy GLucose prOfiles in Women With and Without GDM Risk Factors: EARLY-GLOW (EARLY-GLOW)

Background:

Gestational diabetes mellitus (GDM) is associated with increased maternal and neonatal complications, including macrosomia, preeclampsia, and long-term metabolic consequences for both mother and child. Current screening methods, primarily the oral glucose tolerance test (OGTT), are typically performed between 24 and 28 weeks of gestation and may miss earlier metabolic alterations. Continuous glucose monitoring (CGM) offers a detailed assessment of glucose dynamics and could potentially identify subtle dysglycemia before GDM becomes clinically apparent.

Objective:

The EARLY-GLOW study aims to characterize glucose patterns during early pregnancy and identify CGM-derived thresholds for early dysglycemia in women with and without established risk factors for GDM. The study seeks to determine whether specific combinations of glucose level and duration of hyperglycemic exposure can distinguish women at increased risk of GDM before routine diagnosis. Additionally, it will explore the relationship between glucose profiles and modifiable lifestyle factors such as diet, physical activity, sleep, and stress, while evaluating the feasibility, usability, and acceptance of CGM technology during pregnancy.

Study Design:

EARLY-GLOW is a prospective, decentralized, observational pilot study conducted in Switzerland from July 2026 to June 2027. The study will recruit 48 pregnant women with singleton pregnancies at approximately 12 weeks of gestation. Participants will be stratified into two equal groups: women with at least one recognized GDM risk factor and women without risk factors.

Methods:

Participants will wear a blinded Dexcom G7 CGM continuously from approximately gestational week 12 until routine OGTT screening between weeks 24 and 28 (up to 16 weeks of monitoring). During the study, participants will periodically record fasting blood glucose measurements, dietary intake, meal photographs, sleep quality, physical activity, stress, and well-being through REDCap questionnaires. In the final two weeks of follow-up, participants may additionally use an unblinded FreeStyle Libre 3 CGM to assess user experience. Pregnancy outcomes will be collected approximately six weeks postpartum.

Endpoints:

The primary endpoint is the identification of CGM-derived thresholds combining glucose concentration and duration of exposure that best discriminate between women with and without GDM risk factors. Secondary outcomes include the frequency and duration of hyperglycemic events, time above and below glucose target range, glycemic variability, postprandial glucose excursions, nocturnal glucose patterns, correlations with lifestyle factors, and device adherence and usability.

Study Overview

• Status: Recruiting
• Conditions: Gestational Diabetes

Detailed Description

The EARLY-GLOW study is a prospective, decentralized observational pilot study that aims to improve understanding of glucose regulation during early pregnancy and identify early signs of gestational diabetes mellitus (GDM) before conventional diagnosis. While current GDM screening relies primarily on an oral glucose tolerance test (OGTT) performed between 24 and 28 weeks of gestation, growing evidence suggests that disturbances in glucose metabolism may already be detectable much earlier in pregnancy. Continuous glucose monitoring (CGM) offers the opportunity to capture detailed glucose patterns throughout the day and may reveal subtle abnormalities that are not identified through standard screening methods.

The study will recruit 48 pregnant women with singleton pregnancies at approximately 12 weeks of gestation from across Switzerland. Participants will be stratified into two groups: women with at least one established risk factor for GDM and women without known risk factors. Risk factors include obesity, previous gestational diabetes, a family history of type 2 diabetes, polycystic ovary syndrome, previous macrosomic offspring, bariatric surgery, and certain ethnic backgrounds associated with increased GDM risk.

After enrolment, participants will wear a blinded Dexcom G7 continuous glucose monitor for approximately 12 to 16 weeks, covering the period from early pregnancy until routine GDM screening. Because the sensor is blinded, participants will not be able to see their glucose values during the main observation period, minimizing the risk that knowledge of glucose levels influences behavior. At regular intervals, participants will also record fasting blood glucose measurements, upload meal photos, document nutritional intake, and complete questionnaires regarding sleep, stress, well-being, physical activity, and pregnancy-related symptoms. During the final two weeks of follow-up, participants may additionally wear an unblinded FreeStyle Libre 3 sensor to evaluate user experience and compare acceptance of the two most commonly used CGM systems in Switzerland.

The primary objective of the study is to identify CGM-derived thresholds that characterize early dysglycemia in pregnancy. Rather than focusing solely on a glucose value, the study aims to determine combinations of glucose level and duration of exposure that best distinguish women with and without GDM risk factors. This approach acknowledges that the clinical significance of elevated glucose levels may depend not only on how high glucose rises, but also on how long those elevations persist.

Secondary objectives include comparing the frequency and duration of hyperglycemic episodes between risk groups, assessing time spent above and below target glucose ranges, evaluating measures of glycemic variability, and characterizing postprandial and nocturnal glucose patterns. The study will also investigate the relationship between glucose profiles and lifestyle factors such as diet, sleep quality, physical activity, stress, and well-being. Furthermore, participant adherence, device wear time, comfort, usability, and acceptance of the CGM systems will be assessed to determine the feasibility of large-scale CGM use during pregnancy.

To analyze the data, researchers will use both traditional statistical methods and exploratory pattern-recognition techniques. Receiver operating characteristic (ROC) analyses will be applied to identify glucose thresholds and durations that best discriminate between women at higher and lower risk of GDM. In addition, clustering and glucose-profile analyses will be used to describe different glycemic phenotypes during pregnancy and to identify potentially clinically relevant patterns.

The study is observational, no therapeutic interventions are performed. Participants may benefit indirectly from the nutritional consultation offered at the end of the study, during which glucose data and dietary habits are reviewed with a nutrition specialist. More importantly, the knowledge generated by the study may contribute to improved screening strategies, earlier identification of women at risk for GDM, and the future development of personalized preventive interventions.

• Study Type: Observational
• Enrollment (Estimated): 48

Contacts and Locations

• Study Contact: Name: Stefanie Hossmann, MSc; Phone Number: +41794217376; Email: stefanie.hossmann@dcberne.com
• Study Contact Backup: Name: Martina Rothenbühler, PhD; Phone Number: +41792628989; Email: martina.rothenbuehler@dcberne.com

Study Locations

• Switzerland
  • Canton of Bern
    • Bern, Canton of Bern, Switzerland, 3010
      • Recruiting
      • DCB Research AG
      • Contact: Stefanie Hossmann, MSc; Phone Number: +41794217376; Email: stefanie.hossmann@dcberne.com
      • Contact: Martina Rothenbühler, PhD; Phone Number: +41792628989; Email: martina.rothenbuehler@dcberne.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

The study plans to recruit 48 pregnant women who are approximately in the 12th week of gestation (GW).

Potential study participants will be stratified into two mutually exclusive groups: individuals without risk factor according to the Swiss Expertenbrief No. 8118 or at least one with the exception of age >35 years, which will not be considered for the stratification allocation. The following risks will be considered:

• History of bariatric surgery
• Pre-pregnancy BMI >30 kg/m²
• Non-European background (Africa, Asia, Latin America)
• First-degree relative with type 2 diabetes
• Previous gestational diabetes
• Previous macrosomic (>4000 g) offspring
• Diagnosis of polycystic ovary syndrome (PCOS) or polyendocrine metabolic ovarian syndrome (PMOS)
• Early pregnancy symptoms suggestive of diabetes (e.g. frequent urination, excessive thirst, glucosuria)

Description

Inclusion Criteria:

• Female sex
• Aged ≥18 years at inclusion
• Pregnant with singleton ≤12 GW
• Willingness to wear a CGM device for 12-16 weeks
• Signed informed consent

Exclusion Criteria:

• Pre-existing type 1 or type 2 diabetes mellitus or known prediabetes
• Diagnosis of GDM during current pregnancy
• Known allergy to adhesive materials or sensor components
• Inability to follow procedures or insufficient knowledge of project languages (German, French or English)
• Inability to give consent.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Pregnant women with at least one risk factor for GDM; Risk factors include obesity, previous gestational diabetes, a family history of type 2 diabetes, polycystic ovary syndrome, previous macrosomic offspring, bariatric surgery, and certain ethnic backgrounds associated with increased GDM risk.
Pregnant women with no risk factors for GDM; Risk factors include obesity, previous gestational diabetes, a family history of type 2 diabetes, polycystic ovary syndrome, previous macrosomic offspring, bariatric surgery, and certain ethnic backgrounds associated with increased GDM risk.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
CGM-derived threshold(s) for early dysglycemia during pregnancy	Identification of one or more continuous glucose monitoring (CGM)-derived thresholds combining glucose concentration and duration of hyperglycemic exposure that best discriminate between pregnant women with and without risk factors for gestational diabetes mellitus (GDM). Thresholds will be identified using receiver operating characteristic (ROC) analyses based on CGM data collected during early pregnancy.	From 12 weeks of gestation until routine OGTT screening (24-28 weeks of gestation; up to 16 weeks of CGM monitoring)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of hyperglycemic events per day	Mean number of hyperglycemic events per participant per day, defined as sensor glucose values >7.8 mmol/L for at least 10 consecutive minutes.	From 12 to 28 weeks of gestation (during CGM wear period)
Time spent above 7.8 mmol/L	Average duration per day (minutes/day) with sensor glucose values >7.8 mmol/L.	From 12 to 28 weeks of gestation
Time above 7.8 mmol/L and time to >7.8 mmol/L after logged-in meals	Time after logged-in meal that individual spends >7.8 mmol/L and timing when first value postprandial >7.8 mmol/L	From 12 to 28 weeks of gestation
Time to Return to Preprandial Glucose Following Meals	Time required for postprandial glucose levels measured by continuous glucose monitoring (CGM) to return to the pre-meal glucose value after participant-logged meals.	From 12 to 28 weeks of gestation
Mean 24-hour glucose concentration	Average sensor glucose concentration (mmol/L) over a 24-hour period during the monitoring phase.	From 12 to 28 weeks of gestation
Time above range (TAR)	Percentage of time with sensor glucose values >7.8 mmol/L as measured by CGM.	From 12 to 28 weeks of gestation
Time below range (TBR)	Percentage of time with sensor glucose values <3.5 mmol/L as measured by CGM.	From 12 to 28 weeks of gestation
Glycemic variability	Glycemic variability assessed using standard deviation (SD) and coefficient of variation (CV) of CGM glucose values.	From 12 to 28 weeks of gestation
Nocturnal glucose profile	Mean nocturnal glucose concentration (mmol/L) during predefined nighttime hours.	From 12 to 28 weeks of gestation
Nocturnal hypoglycemia	Percentage of nighttime spent with sensor glucose values <3.5 mmol/L.	From 12 to 28 weeks of gestation
Association between CGM metrics and lifestyle factors	Correlation between CGM-derived glycemic metrics and participant-reported measures of dietary intake, sleep quality, physical activity, and stress.	From 12 to 28 weeks of gestation
CGM adherence	Adherence to CGM use measured by percentage of planned monitoring time with valid sensor data and discontinuation rates.	From 12 to 28 weeks of gestation
Device-related adverse events	Number and nature of device-related adverse events, including skin reactions and technical issues associated with CGM use.	From first sensor application until end of follow-up (up to 16 weeks)
CGM device usability and acceptance	Participant-reported usability and acceptability of Dexcom G7 and FreeStyle Libre 3, including ease of use, comfort, wearability, and overall user experience. The quesions are assessed on a scale from one to five with five being the most positive score.	End of follow-up (26-28 weeks of gestation)

Collaborators and Investigators

• Sponsor: DCB Research AG
• Investigators: Study Chair: Jardena Puder, Prof, Centre Hospitalier Universitaire Vaudois (CHUV)

Study record dates

Study Major Dates

• Study Start (Actual): August 19, 2026
• Primary Completion (Estimated): April 30, 2027
• Study Completion (Estimated): April 30, 2027

Study Registration Dates

• First Submitted: August 20, 2026
• First Submitted That Met QC Criteria: August 20, 2026
• First Posted (Actual): August 24, 2026

Study Record Updates

• Last Update Posted (Actual): August 26, 2026
• Last Update Submitted That Met QC Criteria: August 24, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: risk factors; gestational diabetes; dysglycaemia; decentralizes study
• Additional Relevant MeSH Terms: Urogenital Diseases; Endocrine System Diseases; Female Urogenital Diseases and Pregnancy Complications; Metabolic Diseases; Pregnancy Complications; Glucose Metabolism Disorders; Diabetes Mellitus; Nutritional and Metabolic Diseases; Diabetes, Gestational
• Other Study ID Numbers: EARLY-GLOW

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No